Is jumbo jet aproper noun

No, the compound noun 'jumbo jet' is a common noun, a general Word for a type of large airplane; also called a 'wide body plane', also a common noun.

A proper noun is the name of a specific person, place, or thing. Examples of proper nouns for the common noun 'jumbo jet' are:

• Boeing 747
• Boeing 777
• Airbus A380